Vascular Test Prep Flashcards
Difference between CVA and TIA?
CVA is permanent or semi-permanent impairment, while TIA is a mini stroke, with symptoms lasting under 24 hours.
Vertebral-basilar symptoms (AKA back of the brain symptoms)
- drop attacks
- blackouts
- syncope
- Memory loss
- Vertigo
- Dizziness
- Diplopia
Causes of CVA
- Cardiac: emboli or cessation of perfusion
- Carotid etiology=50%: ischemia, thrombosis-occlusion, emboli to brain
- Aneurysm rupture: intracranial hemorrhage, vasospasm
Risk factors of Cerebrovascular Disease (Atherosclerosis):
family history of Peripheral Artery Disease or Heart Disease Smoking Old Age Diabetes Mellitus Hypertension High Cholesterol/Hyperlipidemia
What % of population has an intact Circle of Willis?
50%
Carotid Artery scanning protocol:
Pt. history Transverse imaging Longitudinal imaging Color Doppler Spectral Doppler "mapping" of any areas of flow disturbance Bruit
ECA is ________, while ICA is _________.
medial, lateral
Where do you scan from to get the carotid best?
Posterolateral
Anatomical Differences between ICA and ECA:
- Posterior Position of ICA
- branches of ECA
- ICA is larger, though not reliable with disease
Doppler waveform differences between ICA and ECA:
ICA=low resistance
ECA= high resistance (oscillations with temporal tap)
From the distal CCA, pivot the probe towards the ______ to view ECA, and towards the ______ for the ICA.
chin, bed
Which view gives most accurate view of plaque?
Transverse
Color scale for arterial scans
around 30
Color scale for venous scans
around 12
What does Color Doppler Flow Imaging evaluate for? (3 things)
- presence of flow
- direction of flow
- quality of flow (laminar vs. turbulent)
Two ways to acquire an angle
- Rock probe (heel-toe)
2. steer the color box
What does perpenducular incidence look like?
both red and blue are seen
Direction of blood flow in neck artery:
right side of screen to left
Direction of blood flow in neck vein:
left side of screen to right
Bulb of CCA may show
Eddy flow/flow separation
Maintain a spectral doppler angle as close to ___ as possible.
60 degrees
Angle correct to _____ wall.
posterior
Overangle correction results in
overestimation of velocities
Triangle F=
Detected Frequency shift
Fo=
Transmitted Freq.
2=
Transmit/receive time
c=
speed of sound in soft tissue
V=
velocity of blood
Cos Theta=
cosign of incidence angle
Doppler sample locations
Prox, Mid, Dist CCA and ECA, and Dist ICA
4 steps to mapping a stenosis:
- Visualize Plaque
- Work Doppler sample volume through the stenotic region (3D)
- Record and Measure highest velocity (take 2 or 3 samples)
- Sample and record distal to stenosis to detect turbulence (if any)
When looking for possible trickle flow, use
low scale (reduced PRF)
What does NASCET stand for?
North American Symptomatic Carotid Endarterectomy Trials
What does ACAS stand for?
Asymptomatic Carotid Atherosclerosis Study
Consensus goals of 2003 Society of Radiologists in US:
- to simplify the confusing array of various criteria
- to standardize categories and thresholds
What did the NASCET study show?
A benefit to carotid endarterectomy (CEA in SYMPTOMATIC patients with a >/= 70% diameter reduction
Consensus recommendations for standardization:
- exams performed by accredited organization
- Doppler angles should be 60 degrees or less
- ICA should be interrogated from bulb to distal segment to reach maximu stenotic region
- Report should include velocities,etc
- On angiograms, the stenosis should be measured using the NASCET method
- VELOCITY MEASUREMENTS FOR ICA STENOSIS SHOULD BE OBTAINED FROM THE POINT OF MAXIMUM STENOSIS
What is the ICA PSV and ICA EDV for a normal degree of stenosis?
PSV= <40
What is the ICA PSV and ICA EDV for <50% degree of stenosis?
PSV= <40
What is the ICA PSV and ICA EDV for a 50-69% degree of stenosis?
PSV= 125-230, EDV= 40-100
What is the ICA PSV and ICA EDV for a >/=70 but < total occlusion degree of stenosis?
PSV=>230, EDV= >100
What is the ICA PSV and ICA EDV for near occlustion?
PSV= high, low or undetectable; EDV= Variable
What is the ICA PSV and ICA EDV for total occlusion?
PSV= undetectable, EDV= N/A
Three potential characteristics of plaque morphology:
- Homogenous
- Heterogenous
- Calcified( presence of acoustic shadow)
Indications for imaging the vertebral arteries:
Primary: for detection of flow direction
Also: to evaluate for abnormal waveforms indicating stenosis or occlusion
Indications for imaging the subclavian arteries:
Primary: for detection of subclavian stenosis
Also: to follow up after a difference in arm pressures is detected
A _______ gradient between left and right brachial pressures suggests subclavian stenosis?
20mmHg, arm with lower pressure has stenosis!
When does a subclavian steal occur?
When there is an occlusion blocking blood from getting to a subclavian artery, blood is rereouted
Early systolic deceleration (ESD)
AKA Bunny Rabbit waveforms, changing pressure patterns in the left arm in the presence of proximal subclavian artery stenosis affect the vertebral waveforms.
